This invention relates generally to magnetic resonance imaging (MRI) and, more particularly, the invention relates to fast spiral T.sub.2 -weighted imaging.
Magnetic resonance imaging (MRI) is a non-destructive method for the analysis of materials and represents a new approach to medical imaging. It is generally non-invasive and does not involve ionizing radiation. In very general terms, nuclear magnetic moments are excited at specific spin precession frequencies which are proportional to the local magnetic field. The radio-frequency signals resulting from the precession of these spins are received using pickup coils. By manipulating the magnetic fields, an array of signals is provided representing different regions of the volume. These are combined to produce a volumetric image of the nuclear spin density of the body.
T.sub.2 -weighted abdominal tumor imaging is a difficult problem, mainly because of motion artifacts and limited SNR and resolution. Spiral scanning can reduce abdominal motion artifacts by reducing the scan time, preferably to under a breath-hold, and because of the intrinsic robustness of spiral scanning in presence of motion. Further, spiral scanning produces few objectionable motion artifacts because the center of k space is scanned redundantly, the moments of spirals of well-behaved, and the artifacts are spiral rather than coherent ghosts. Spiral scanning addresses the problem of limited SNR by using long readout periods and the problem of limited resolution by efficiently scanning k space.
The present invention is directed to T.sub.2 -weighted interleaved spiral scanning which is particularly useful for abdominal tumor imaging.